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Every piece of hardware in a commercial door specification is constrained by the frame before a single product is selected. The frame determines which lock functions are physically possible, which hinge gauge is required, where the closer can mount, what strike dimensions the electric strike must match, and whether a cylindrical or mortise lockset is compatible with the existing door preparation. Selecting hardware without verifying frame type and preps produces the most expensive field corrections in commercial work because the correction always involves either frame modification or hardware return, and frequently both.

Hollow Metal Frames: The Commercial Standard

Hollow metal door frames are formed from cold-rolled steel sheets bent into channel-profile sections with welded or mechanically fastened corners. They accept standard ANSI hardware preparations, provide a rigid mounting surface, and satisfy fire rating requirements when properly assembled and anchored.

The closer reinforcement channel welded inside the frame header must match the closer model's mounting footprint and be positioned for the specified arm configuration. A frame ordered with closer reinforcement in the wrong location for the parallel arm configuration requires field modification, which weakens the frame at the modification point.

Welded vs. Knocked Down (KD) Frames

Welded frames have continuously welded corner joints fabricated as a single rigid unit, standard for new construction where the frame is set in masonry or concrete before the walls are built. KD frames ship with head and jambs as separate components assembled in the field. KD frames are the correct choice for retrofit applications, remodel projects, and any situation where the frame must be assembled in place.

Standard Door Frame Preps

ANSI A115.2 (cylindrical) is the standard strike prep for cylindrical locksets: a 4-7/8" x 1-1/4" faceplate opening with a keeper pocket for the cylindrical latch bolt. ANSI A115.1 (mortise) is the strike prep for mortise locksets: a wider, taller opening for the flat mortise latch bolt. ASA standard has rounded corners at 1/8-inch radius, common in pre-1980 construction. The electric strike faceplates guide covers how to measure an existing frame cutout to determine which standard it was built to.

Hinge preps are reinforcement pockets in the jamb at the three standard hinge locations. Standard commercial hinge reinforcement accommodates 4.5" x 4.5" hinges. Browse commercial door hinges and spring hinges with gauge and load specifications.

Aluminum Storefront Frames: A Different Hardware Universe

Aluminum storefront frames are not interchangeable with hollow metal frames from a hardware compatibility standpoint. Aluminum storefront stiles are narrow at 1-3/4" to 2" wide and hollow aluminum rather than solid steel. Hardware designed for aluminum storefront, specifically Adams Rite locks, storefront deadlatches and flushlocks, and storefront trims, is engineered for this constraint and is not interchangeable with hardware designed for hollow metal.

The [storefront hardware selection guide](https://nationallocksupply.com/blog/how-to-choose-storefront-hardware-for-aluminium-doors/) covers lock type selection and stile dimension requirements. The complete storefront bolts and latches selection includes Adams Rite, Keedex, and ACSI options.

Double Door Frame Configurations

Double door openings with a center post allow each leaf to latch independently to the post using standard hardware. Double door openings without a center post require the active leaf to latch to the frame and the inactive leaf to be secured by flush bolts at top and bottom, with a door coordinator ensuring the inactive leaf closes before the active leaf contacts the astragal.

Flush bolts and coordinators must be UL-listed for fire-rated double door assemblies. The flush bolts specification guide covers function and sizing for each configuration.

Retrofitting Hardware to Damaged Frames

Door wrap-around plates reinforce the door edge at the lock location and cover damaged material around the lock prep. Latch protectors protect the frame strike area from pry attacks by covering the gap between the door edge and frame that forms the attack point.

Frame Finish and Corrosion

Primed frames are standard for interior applications where the frame will be painted. Galvanized frames are required for exterior applications and any frame installed in a slab pocket with below-grade moisture exposure. Stainless steel frames are appropriate for high-humidity interior environments including commercial kitchens, natatoriums, and locker rooms.